Objective: For secondary adrenal insufficiency (SAI), established biochemical parameters for dosage control are lacking and no optimal substitution dosage and daily distribution have been determined yet. Therefore, in clinical practice, the individual total dose is often adjusted based on patients' subjective well-being. Design: Effects of three standard glucocorticoid replacement regimens on psychological variables were assessed in patients with SAI based on a randomized double-blind study design. Methods: SAI patients (nZ18) were treated with three different established glucocorticoid replacement regimens in a randomized, double-blind, crossover study (treatment A, hydrocortisone 10 mg-placebo-5 mg-placebo; treatment B, hydrocortisone 10 mg-5 mg-placebo-5 mg; and treatment C, prednisone 5 mg-placebo-placebo-placebo). Following each 4-week replacement regimen, quality of life (SF-36) and emotional distress (brief symptom inventory (BSI)) were assessed along with diurnal changes in current well-being (Bf-S) and alertness (Stanford Sleepiness Scale (SSS)) using validated questionnaires, and additionally compared with patient (patients with pituitary disease and adrenal sufficiency) and healthy control groups. Results: SAI patients showed improvements in physical quality of life (i.e. SF-36 physical function, P!0.05; physical role function, P!0.05) and current well-being (at 1800 h, P!0.05) under treatment A (hydrocortisone 10-0-5-0 mg) compared with the other replacement regimens. Quality of life and current well-being were significantly impaired compared with healthy controls but did not differ from patient controls. Conclusions: Although the observed improvements in psychological parameters were comparatively small, our results indicate beneficial effects of a 10-0-5-0 mg hydrocortisone replacement regimen. Nevertheless, treatment effects were insufficient to restore subjective health compared with healthy controls, indicating the need for improved replacement regimens and supportive psychosocial interventions in SAI patients.